The invention is directed to improvements in position transducers. A position transducer is already known (German Patent Application No. 34 11 456 C2), in which a gas pedal position of a motor vehicle is converted into a rotary position of a transducer shaft, in order by means of a rotary potentiometer to generate an electrical adjusting signal corresponding to the pedal position.
In this kind of position transducer, the transmission of the gas pedal position to the transducer shaft is effected by a tension--or compression-loaded transmission member, which may be embodied as a connecting rod or--in the case of a tensile load--as a Bowden cable. The transmission member is connected on one end to an actuating member that is embodied either by the gas pedal of the motor vehicle itself, or by a further component actuatable by the gas pedal. On its other end, the transmission member is connected to a drive member, which is disposed on the transducer shaft in a manner fixed against relative rotation.
The transducer shaft of the position transducer is acted upon by means of at least one restoring spring with a restoring torque, whose magnitude in terms of amount is dependent on the particular rotary position of the transducer shaft at the time, between an idling position and a full-load position. An adjusting force acting upon the motor vehicle gas pedal is converted into an adjusting torque counteracting the restoring torque, by means of the actuating member, transmission member, and driver member. To avert damage, the transducer shaft upon reaching the full-load position must be prevented from being acted upon by an impermissibly strong adjusting torque, to which a maximum-permissible adjusting force corresponds.
This can be done for instance by making the gas pedal in the full-load position of the transducer shaft come to rest on an external full-load stop connected to the vehicle relative to the gas pedal. A portion of the adjusting force exceeding the maximum allowable adjusting force is then absorbed by the vehicle bottom.
The disadvantage is that for tolerance reasons, an adjustable full-load stop is required, which in an expensive labor step must be adapted to the full-load position of the position transducer after the position transducer has been installed in the vehicle. Moreover, the adjustment of the full-load stop must be checked at regular intervals (for instance on the occasion of an inspection) and readjusted, since if the full-load stop is adjusted incorrectly, damage and even failure of the position transducer are possible.